Right now, if I want to buy a little land over my maxxed-out tier, I have to jump to the new tier fee, and pay an amount as though I have bought land up to that tier's maximum.
Instead, what should happen is that if i go over my tier, the next tier's per-square-meter rate should be applied to that land purchase. So that rather than spending a huge amount of new tier fee for the little amount i want to buy, the additional fee I would pay would be the fraction of the next tier fee.
The fraction would be the amount of land over my current tier -over- the difference between the next tier fee minus my current tier fee.
This would encourage all kinds of small land purchases and eliminate tiny unused land parcels that exist beween current landholdings, that only exist now, because people dont want to go over their current tier.